In recent publications, such as, "Quantized Acoustic Phonon Modes in Quantum Wires and Quantum Dots," Stroscio et al, Journal of Applied Physics, Vol. 76, pg. 4670 (1994), acoustic phonons have been quantized for a variety of nanoscale and mesoscopic structures in order to assess the role of electron/acoustic-phonon scattering in limiting the performance of nanoscale and mesoscopic electronic devices. These structures/devices include quantum wells, quantum wires with cylindrical and rectangular cross-sections, and quantum dots with spherical, cylindrical, and rectangular boundaries. These quantized phonons have been studied for two cardinal boundary conditions of classical acoustics: free boundaries (open boundaries) where the phonon displacements are unrestricted and allowed to balance all normal traction forces to zero; and clamped boundaries (rigid boundaries) where phonon displacements are required to vanish at the boundaries. For quantum wells, scattering rates have been calculated for free-standing structures. See for example, "Confined Acoustic Phonons in a Free-Standing Quantum Well," Bannov et al, Proceedings of the 1993 International Semiconductor Device Research Symposium, pg. 659. For the case of quantum wires, scattering rates have been calculated only for the case of infinitely long quantum wires and only in the lateral dimensions. However, for realistic mesoscopic devices designs, the quantum wire input and output "leads" as well as the active regions of the devices with quantum wire geometries obviously have finite lengths. Accordingly, deformation and piezoelectric scattering rates must be based on acoustic phonons that are quantized in all three spatial dimensions. However, heretofore, those skilled in the art have not considered the role of three dimensional confinement of acoustic phonons in mesoscopic devices.
Accordingly, it is a great challenge in the application of quantum based devices to consider the molecular feature-size implicit in nanoelectronic and mesoscopic technology. Many of these challenges concern fluctuations, tolerances, robustness, and other statistical considerations which conceivably negate many of the seemingly fragile characteristics of nanodevices. There are many illustrative examples in which inherent statistical variations in composition and device dimensions produce substantial deviation from the desired nanostructure electrical response. These examples include: minimum metal-oxide-semiconductor transistor size as determined by a combination of gate oxide breakdown, drain-source punch-through and substrate doping fluctuations; minimum planar bipolar transistor size as determined by a combination of collector junction breakdown, base punch-through and base doping fluctuations; effects of structural and alloy disordering on, the electronic states in quantum wires; and the effect of fabrication-related dimensional variations on carrier scattering rates in quantum wires.
Some prior proposed ways to overcome these problems and to achieve a more robust device include the application of Coulomb blockade effects, design through quantum control theory, and emulation of biological and chemical systems, such as neuron networking and self-organization finesse disordering processes. For example, potential applications of quantum control theory to "small" and mesoscopic electronic devices are motivated based on past uses of robust optimal control theory for the selective excitation of quantum mechanical vibrational states of molecules. See for example, Shi et al, "Optimal Control of Selectivity of Unimolecular Reactions via an Excited Electronic State with Designed Lasers," Journal of Chemical Physics, 97, pgs. 276-287. Additionally, a number of important, recent developments have included: the observation of Coulomb blockade effects at temperatures which are an appreciable fraction of room temperature; theoretical prescriptions for enhancing the reliability of single electron switches operating on the basis of Coulomb effects; and recent progress in understanding how mesoscopic Coulomb blockade effects may be used to greatly suppress noise in electron emission processes in p-i-n semiconductor junctions as well as in p-n microjunctions. The observation of Coulomb blockage effects at 100 degrees Kelvin has been extended recently by the principal authors of Leobandung et al, "Observation of Quantum Effects and Coulomb Blockage in Silicon Quantum Dot Transistors at Temperatures Over 100 Kelvin," Journal of Applied Physics, to 110 Kelvin for the case of holes and 170 Kelvin for electrons.
Heretofore, mesoscopic electronic devices functioning on the basis of de Broglie wave inference phenomena have been defined by the international community to realize high functionality with effectively very high data rate processing capabilities. These mesoscopic devices designs, however, are generally based on the assumption that deformation potential and piezoelectric scattering processes can be neglected and that other inelastic scattering mechanisms are absent. This assumption of negligible deformation potential and piezoelectric scattering rates is usually made for convenience of the device designer and it has not been demonstrated that mesoscopic electronic devices can be realized with the needed levels of de Broglie wave coherence when deformation potentials and piezoelectric scattering are accounted for properly.
As a result, no one heretofore has been able to tailor the deformation potential and piezoelectric scattering in mesoscopic devices in order to maintain de Broglie wave coherence. The present invention fulfills this need.